To be a commercial success it is critical to understand and drive towards meeting the needs of your sweet spot, pragmatic customer who is looking for results, a dependable relationship and low risk.Open Source will not magically sell any easier because there's something special about it per se, but rather because it helps properly align a software company with Michael's points above.
Having worked in the software industry for 18 years, I've seen numerous instances where a company effectively taps into a need at first... only to trip under their own momentum. The single, biggest contributing factor?
They lost touch with their customers.
Open Source may facilitate such alignment, but all the same marketing, pricing model, strategy, and execution discussions remain. And once you have that nailed, don't ever, EVER, forget who got you there -- your customers, not OSS.
Think of it as a tool, a construct: and a great one at that. However, OSS is not a business model. Keep focus on your customers and competitors, and use open source as a differentiator -- not vice versa.